Among existing communication equipments, PBX is widely used for internal communication in a business consortium. However, a consortium often has branches in different cities or a same city, wherein each branch accesses to telecom network via a PBX. For communication between two branches, the calling party has to dial the PBX switchboard number of the called party, and then dial the extension number after listening to a voice prompt.
Hereunder the communication flow between users of different PBXs in a consortium is explained by way of example. It is assumed that the consortium has a branch in location A, whose internal communication is managed by a PBX with a switchboard number of 02188888888 and an outgoing call prefix of 0, and a short number of employee S1 in which branch is 210011; and another branch in location B, whose internal communication is also managed by a PBX with a switchboard number of 01022222222 and an outgoing call prefix of 0, and a short number of employee B1 in which branch is 10001. The flow of employee S1 calling employee B1 is shown in FIG. 1, as follows:
1. employee S1 lifts off the hook and dials 0 to seize a PBX circuit;
2. after hearing a second dial tone, employee S1 dials the switchboard number 01022222222;
3. after analyzing the number, the system determines to route the call to location B, and then the terminal office in location B routes the call to the corresponding PBX;
4. the PBX in location B plays back a voice prompt “please dial the extension number”;
5. employee S1 dials employee B1's extension number 10001;
6. the PBX in location B rings B1′ extension, and then B1 picks up the phone to talks with S1.
With the above method, when users of different PBXs in a same consortium call each other, the calling party has to dial the number of the PBX switchboard to which the called party belongs and then dial the extension number of the called party, resulting in dialing complexity and reduced communication efficiency.
Though the existing Wide Area Centrex (WAC) service can provide prompt short-number dialing service for branches of a consortium in different locations, it can only allocate short numbers for a PBX switchboard number. To call each other, users of different PBXs still need to dial the short switchboard number firstly and then dial the extension number of the called party. Hereunder a WAC-controlled communication flow between users of different PBXs in a consortium is explained by way of example:
It is assumed that the consortium has a branch in location A, whose internal communication is managed by a PBX with the switchboard number as 02188888888 and the outgoing call prefix as 0, and the short number of employee S1 in which branch is 210011; and another branch in location B, whose internal communication is also managed by a PBX with a switchboard number of 01022222222 and an outgoing call prefix of 0, and the short number of employee B1 in which branch is 10001; and the switchboard numbers of branch A and B are both incorporated into the consortium's WAC, wherein the short WAC number of the PBX in location A is 218888, and that of the PBX in location B is 106666. The flow of employee S1 calling employee B1 is shown in FIG. 2, as follows:
1. employee S1 in location A lifts off the hook and dials 0 to seize a PBX circuit;
2. after hearing a second dial tone, employee S1 dials the switchboard number 106666 of location B;
3. after analyzing the number, the system determines to route the call to location B, and then the terminal office in location B routes the call to the corresponding PBX;
4. the PBX in location B plays back a voice prompt “please dial the extension number”;
5. employee S1 dials the extension number 10001 of employee B1;
6. the PBX in location B rings B1′ extension, and then B1 picks up the phone to talks with S1.
It is seen that when users of different PBXs in a same consortium call each other, the calling party still has to dial the short WAC number of the PBX switchboard to which the called party belongs and then dial the extension number, by which only the switchboard number is abbreviated by several digitals, therefore the problem of complex dialing and low communication efficiency is not solved radically.